Electrical adapter



Dec. 8, 1970 P. PURER ELECTRICAL ADAPTER 2 Sheets-Sheet 1 Filed March 19, 1969 JAIME/V706 cl /1.4 P0252,

5 Ms rr'0eA/s Z Dec. 8, 1970 P. PURER 3,546,650

ELECTRICAL ADAPTER Filed March 19, 1969 2 Sheets-S leet 2 J/Q -Ma1a. 1%

1!! pa /1:41p fi/QEQ,

6 A48 4rraeMEys- United States Patent '0 U.S. Cl. 337-91 Claims ABSTRACT OF THE DISCLOSURE An electrical adapter which provides circuit protection against overloads and short circuits. The adapter contains a plug and receptacle suitable for use with standard, office and household electrical equipment. A circuit breaker, connected between the plug and the receptacles, is contained within a housing to which the plug and receptacles are coupled. The plug of the adapter contains a ground pin which is readily removable from the plug when the plug is to enagage an outlet or receptacle not adaptable for receiving a ground pin.

BACKGROUND OF THE INVENTION Field of the invention The invention relates to electrical adapters, particularly those suitable for use with standard office and household electrical equipment.

Prior art Circuit protection means such as fuses and circuit breakers, have been consistently used in homes and oflices to protect electrical circuits. Typically, all the fuses or circuit breakers are located in a single compartment and each fuse or circuit breaker protects a particular segment of the electrical wiring in an oflice or home. Thus, if a single fuse or circuit breaker interrupts the flow of current due to an overload or short circuit, electrical power is cut off in an entire segment of the ofiice or home. Generally, a room or a number of rooms may be affected because of the overload or short circuit associated with a single outlet.

When a fuse or circuit breaker interrupts the current in several rooms of a house, it is often difficult to determine which electrical device caused the overload or short circuit. Generally, every electrical devicecoupled to the interrupted circuit must be disconnected and then reconnected one at a time to isolate the faulty device. In situations where the interruption of power was due to an overload caused by the cumulative power requirement of several devices, it is even more difiicult to isolate these devices. Thus, to isolate a problem may require several trips between the circuit breaker or fuses and the location of the interrupted circuit.

Since it is common for a single fuse or circuit breaker to protect several outlets, the allowable circuit flow through each such device is more than that required by a single appliance. Thus, it is possible for an appliance to be defective, draw much more than its normal current and not cause the fuse or circuit breaker to interrupt the current.

SUMMARY OF THE INVENTION An electrical adapter which provides overload and short circuit protection is described. A standard electrical plug comprising a pair of projecting prongs and a ground pin is coupled to a housing. A circuit breaker, contained within the housing, is coupled to one of said prongs. A plurality of electrical receptacles, each containing three contacts, is also contained within the housing. One of the contacts is coupled to one of the prongs of the plug, another is coupled to the circuit breaker and the third contact is coupled to the ground pin. Means are provided for resetting the circuit breaker exterior to the housing. The ground pin threadingly engages the plug allowing the pin to be readily removed when the plug is to engage a receptacle or outlet not adaptable for receiving a ground pin.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the adapter in which the plug of the adapter is visible.

FIG. 2 is a perspective view of the adapter in which the circuit breaker housing of the adapter is clearly visible.

FIG. 3 is a cross section of the adapter taken through section 3-3 of FIG. 1.

FIG. 4 is a perspective vieW of the adapter when the receptacle housing is separated from the circuit breaker housing.

FIG. 5 is an electrical schematic illustrating the connections between the plug and the contacts contained within the receptacles.

FIG. 6 is a cross section of the circuit breaker taken through section 66 of FIG. 3.

FIG. 7 is a perspective view of an alternate embodiment of the adapter.

FIG. 8 is a cross section of the adapter taken through section 88 of FIG. 7.

FIG. 9 is a cross sectional view of the adapter taken through section 99 of FIG. 7.

FIG. 10 is an electrical schematic of the adapter illustrated in FIGS. 7 through 9.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 and 2, the electrical adapter 2 described herein is illustrated in perspective views. In FIG. 1, plug 10 comprising projecting prongs 11 and 12 and ground pin 23 is visible. Two receptacles 46, each comprising three aperatures extending into receptacle housing 22, are illustrated in FIGS. 1 and 2. The adapter 2 contains four receptacles or outlets 46, each adaptable for receiving a plug such as plug 10. The circuit breaker housing 32 which is coupled to housing 22, is shown with the reset button 58 in FIG. 2.

Referring to FIG. 4, the construction of the adapter housings comprising breaker housing 32 and receptacle housing 22 is illustrated. Receptacle housing 22 consists of a regularly shaped octagonal member having a consistent thickness d. A pair of channels 24 is disposed between two opposite, parallel sides of the housing. The channels 24 extend into housing 22 and have a depth less than d. A second pair of channels 25, similar in dimensions to channels 24, are disposed between opposite, parallel faces of the housing 22 at right angles to channels 24. The channels 24 and 25, when housing 22 is coupled to housing 32, form aperatures adaptable for cooperatively engaging prongs similar to prongs 11 and 12 illustrated in FIGS. 1 and 4. Cavity '31, defined by the interior wall of the housing 22, extends into the housing for a distance les than d. Disposed about the periphery of the cavity 31 are four posts 47. Each post 47 is separated from the interior walls defining cavity 31 by slots 48. The posts 47 which are rigidly coupled to the housing 22 at the base of cavity 31 are elongated members having a cross sectional shape resembling the segment of a circle. Apertures 26, disposed through the housing 22 from the exterior sides of the housing containing channels 24 and 25, communicate with cavity 31. Housing 22 also contains apertures adaptable for allowing the free passage of prongs 11 and 12 which are disposed between cavity 31 and the surface of housing 22 containing plug 10 (FIG. 1).

Circuit breaker housing 32 is a generally rectangular housing having an octagonal flange suitable for engaging 3 housing 22. Both housings 22 and 32 may be made from plastic, rubber, or similar material utilizing commonly known techniques such as molding. When adapter 2 is assembled, housing 32 is coupled to housing 22 by means not shown with prongs 11 and 12 projecting through the receptacle housing 22 as illustrated in FIGS. 1 and 3.

Prongs 11 and 12 are rigidly coupled to the interior of housing 32 by bolt means 36 and 37 illustrated in FIGS. 3 and 4. Prongs 11 and 12 may be standard electrical prongs adaptable for engaging standard household electrical outlets or receptacles. The prongs are typically made from conductive metals such as aluminum or copper.

Ground pin 23, a cylindrically shaped pin, suitable for engaging a standard ground connection of a plug, is illustrated in FIGS. 1, 3 and 4. One end of ground pin 23 is threaded to cooperatively engage thread means 28. Thread means 28 is rigidly coupled to housing 22. Thus, a ground pin 23 is removably attachable to plugs and may be readily removed when plug 10 is to engage a receptacle or outlet which does not have an aperture suitable for receiving the ground pin. Ground bus bars 27, clearly seen in FIG. 4, are electrically coupled to threaded means 28 and are rigidly held within housing 2 by bolt 40. The bus bars 27 extend into apertures 26 and form conductive means between ground pin 23 and the ends of the bars 27. The ends of the bars 27 are formed into cylindrical shapes and disposed within apertures 26, forming contacts suitable for engaging a ground pin such as a ground pin 23 inserted into aperture 26'.

The symmetrically shaped contact bars 13, 14, and 16 have arc-shaped center portions 49 as illustrated in FIG. 4. Each contact bar is adaptable for engaging and is disposed within a single channel 24 and a single channel 25. The are 49 of each bar engages a slot 48 of receptacle housing 22 while the ends of the bar are disposed in the two right angle channels adjacent to the slot 48. Thus, each contact bar is held in place by two right angle channels and slot 48. The ends of each of the bars are adaptable for making electrical connection between the bar and a prong such as prongs 11 or 12 which may be engaging the channel in which the bar is disposed. Note that each of the bars 13 through 16 will have one of its ends in one receptacle 46 and the other of its ends in another receptacle 46. The contact bars may be made from a conductive metal such as copper.

Referring to FIGS. 4 and 5, the electrical connections between projecting prongs 11 and 12 and the contact bars 13 through 16 are illustrated. Prong 11 is directly coupled to the center of contact bar 13 by wire 17. Contact bar 13 is coupled to contact bar 15 by wire 21. The output from the circuit breaker contained within housing 32 is coupled to wire 20 at bolt 35. Wire 20 is coupled to contact bar 16 and contact bar 16 is coupled to contact bar 14 through wire 18.

Referring to FIGS. 3, 4 and 6, the circuit breaker contained within housing 32 is most clearly illustrated. A pair of bi-metallic strips 34a and 34b are each rigidly bolted at one end to housing 32 by bolts 33 and 38, respectively. One end of strip 34a is electrically coupled to strip 56 while the other end of strip 34a is electrically coupled to the other end of strip 3411 by bar 59. Coupled to the center of bar 59 is a non-conducting pin 55. The end of strip 34b which is rigidly coupled to housing 32 is electrically coupled to strip 57 by bolt 38 as illustrated in FIG. 3. Strip 57 provides electrical contact between bolts 38 and 41 and hence between strip 34b and contact arm 52. Each strip 34a and 34b is bi-metallic, such that when the strips become heated due to current passing through them, the strips will bend and pin 55 will move towards spring strip 54. The selection of the materials used for strips 34 may be made in accordance with commonly known technology.

Contact arm 52 which comprises a pair of conducting strips is rigidly held to housing 32 by bolt 41 most clearly seen in FIG. 3. Spring strip 54 which is also coupled to housing 32 by bolt 41 is an elongated strip which is disposed and freely movable between the strips forming contact arm 52. The upper end of spring strip 54 is coupled to contact arm 52 by spring 30. Contact arm 52 is adaptable to move between stop 60 and strip (FIG. 3). The contact arm 52 is held under tension by spring 30 and the combination of contact arm 52, spring strip 54 and spring 30 has only two stable positions; one when arm 52 engages stop 60 and the other when arm 52 is in contact with strip 50 through contact 53. Contact 53 which is coupled to contact arm 52 is adaptable for providing electrical contact between strip 50 and the contact arm when the arm is moved toward the strip 50. Strip 50 is disposed along the back of housing 32 from a point interior to where contact 53 engages the strip 50, to bolt 35. Contact arm 52, spring strip 54 and spring 30 may be ordinary metal parts.

Reset button 58 which is utilized to reset the circuit breaker is an elongated cylindrical member having enlarged ends (FIG. 3). The reset button 58 is disposed through an aperture in housing 32 such that the button may travel freely Within the aperture but is prevented from completely disengaging the aperture because its enlarged ends have a larger diameter than the aperture. Spring 29 is disposed along the reset button between the interior of housing 32 and one end of the reset button.

The operation of a circuit breaker may be readily understood from FIG. 3. Contact arm 52 is shown in its open position in FIG. 3. In order to reset the circuit breaker, reset button 58 is depressed, forcing spring strip 54 to engage pin 55. This movement forces contact arm 52 to move towards strip 50 thereby causing contact 53 to engage strip 50. When this occurs, an electrical path is completed through the circuit breaker. The pathbeginning at prong 12 (FIG. 4) is coupled to bolt 35 via strips 56, 34, 57, contact arm 52, contact 53 and strip 50.

When the electrical current passing through the bimetallic strip 34 reaches a predetermined level, the heating caused by this current causes the strip 34 to bend towards spring strip 54. As this occurs, pin 55 engages spring strip 54 forcing it to change its position and move to the position illustrated in FIG. 3. This causes contact 53 of arm 52 to disengage strip 50, thereby disrupting the current path between prong 12 and contact bars 14 and 16.

While the present adapter utilizes a circuit breaker means containing a bi-metallic strip, it would be obvious to one skilled in the art to utilize any one of numerous circuit interrupting means in place of the described circuit breaker. For example, a fuse or solid state device could be utilized in this application.

With reference to FIGIS. 1 and 2, the operation of the adapter 2 may be readily understood. In a typical office or household application, the plug 10 is inserted to an outlet or receptacle. If the outlet is one which does not have provisions for receiving ground pin 23, the ground pin is removed from the plug. Once plug 10 has engaged a receptacle or outlet, the receptacles 46 may themselves be used as outlets for supplying power to electrical devices. Other plugs are then made to engage the receptacles 46. If an overload should occur from any plug which engages receptacles 46, the circuit breaker contained within housing 32 will interrupt the current flowing to the receptacle 46 and button 58 will extend outwardly from housing 32. When this occurs, the device which causes the overload may be removed and the circuit breaker reset by depressing button 58.

'In one of its applications, the predetermined current at which the circuit breaker opens may be lower than the current at which other circuit protection means in the same line open. For example, if the fuse protecting a portion of the circuitry in a home is capable of handling 30 amps, the circuit breaker in adapter 2 may be made to interrupt the circuit at a current level of 20 amps. Thus, adapter 2 will provide circuit protection that will interrupt the current before the fuse will blow. This will allow the isolation of a faulty device to a particular outlet in the home.

Referring to FIGS. 7 through 10, an alternate adapter 3 is illustrated. The adapter 3 comprises a plug 110 having projecting prongs 111 and 112, and ground pin 123; and a single receptacle 146. The single receptacle is suitable for engaging a plug such as plug 110. Adapter 3 is contained within a housing which comprises a rectangularly shaped lower housing 62 and a trough shaped upper housing 63. The upper housing 63 contains apertures suitable for allowing projecting prongs 111 and 112 to project from the housing, apertures to allow a plug to engage contacts 65 and 66 of receptacle 146 and an aperture 126 adaptable for receiving a ground pin. Projecting prongs 111, 112, ground pin 123 and receptacle 146 may be similar to projecting prongs 11 and 12, ground pin 23, and receptacle 46 previously discussed in conjunction with adapter 2. The housings 62 and 63 of adapter 3 may be similar in construction to housings 22 and 23 of adapter 2.

Projecting prong 111 is coupled to contact 65 through strip 64 as is illustrated in FIGS. 8 and 10. Contacts 65 and 66 are metal contacts adaptable for electrically engaging prongs inserted within receptacle 146. Ground pin 123 threadingly engages the elongated cylindrical member 67 one end of which define the cylindrically-shaped cavity 69. Cavity 69 is adaptable for receiving a ground pin such as pin 123. Member 67 may be made of aluminium or copper or similar conducting material.

A circuit interrupting means is coupled between prong 112 and contact 66. Any suitable circuit interrupting means for interrupting an electrical current when the current reaches a predetermined level may be utilized, such as a circuit breaker or fuse. As illustrated in FIGS. 8

and 9, a circuit breaker similar to that utilized in adapter 2 is illustrated. Members 30, 34a, 34b, 50, 52, 55 and 59 of adapter 2 are again illustrated as members 130, 134a, 13412, 150, 152, 155 and 159, respectively. The operation and the construction of the circuit breaker illustrated in FIGS. 8 and 9 is similar to the circuit breaker utilized in the adapter 2. Adapter 3 also contains a reset means, button 158. The button may be similar to button 58 utilized in adapter 2.

' The operation of apter 3 is identical with that of adapter 2. Plug 110 is inserted into a receptacle or outlet and couples receptacle 146 to that outlet. If the current through the circuit breaker means exceeds a predetermined level, the current supplied to receptacle 146 will be interrupted by the circuit breaker. The circuit breaker may be reset by pressing button 158 as is the case with adapter 2 and button 58.

Thus, an electrical adapter has been disclosed which provides circuit protection between a plug and receptacles contained within a single housing. The plug of the adapter contains a removable ground pin, thereby allowing the adapter to be used both with receptacles adaptable to receive a ground pin and those which do not have provisions for a ground pin.

I claim:

1. An electrical adapter comprising:

a plug comprising at least a first and a second projecting prong adaptable for engaging an electrical receptacle;

a receptacle adaptable for receiving an electrical plug comprising at least a first and a second contact, said first contact being coupled to said first prong;

a circuit breaker coupled between said second prong and said second contact; and

a housing enclosing said circuit breaker and rece tacle, said housing having at least two apertures for receiving a plug which is engaging said receptacle and wherein said circuit breaker includes an elongated contact arm coupled at one end to said housing, a spring strip coupled at one end to said housing, a spring coupled between the other end of said contact arm and said spring strip such that said contact arm, spring strip and spring have two stable positions, a bi-metallic strip positioned within said housing such that when said bi-metallic strip bends it contacts one side of said spring strip thereby causing said contact arm to assume one of its two stable positions and a reset button coupled to said housing and positioned such that it is adaptable for contacting the other side of said spring strips thereby causing the contact arm to assume the other of its stable positions when said button contacts said spring strips;

whereby when a current passing through said circuit breaker reaches a predetermined level, said strip bends and contacts said spring strip causing said contact arm to open the electrical path through the cricuit breaker and when said reset button contacts said spring strip it causes said contact arm to close the electrical path through the circuit breaker.

2. The adapter defined in claim 1 containing a plurality of said receptacle.

3. The adapter defined in claim 1 wherein said plug contains a projecting ground pin and said housing contains an aperture for receiving a ground pin and where an electrical contact coupled to said ground pin is disposed within said aperture such that a ground pin inserted into said aperture is coupled with said contact.

4. The adapter defined in claim 1 wherein said ground pin is removable from said plug.

5. The adapter defined in claim 4 wherein at least one end of said ground pin is threaded and wherein said plug contains threads for cooperatively engaging said threaded ground pin.

References Cited UNITED STATES PATENTS 2,866,033 12/1958 Dillon 337113X 2,894,098 7/1959 Ludwig 337-113 2,783,329 2/1957 Jackson 337l13X FOREIGN PATENTS 794,339 2/1936 France 339-14 BERNARD A. GILHEANY, Primary Examiner 'DEWITT M. MORGAN, Assistant Examiner US. Cl. X.R. 337-ll3, 348 

